CVE-2016-0701
Description
It was found that OpenSSL used weak Diffie-Hellman parameters based on unsafe primes, which were generated and stored in X9.42-style parameter files. An attacker who could force the peer to perform multiple handshakes using the same private DH component could use this flaw to conduct man-in-the-middle attacks on the SSL/TLS connection.
Statement
OpenSSL 1.0.2 provides support for generating X9.42 style parameter files. This feature does not exist in any previous versions of OpenSSL. Therefore versions of OpenSSL shipped with Red Hat Enterprise Linux 5, 6, and 7, and JBoss EAP and JBoss Web Server are not vulnerable to this security flaw.
Versions of OpenSSL shipped in Red Hat Enterprise Linux do not enable the SSL_OP_SINGLE_DH_USE option. However, most applications do not use SSL_CTX_set_tmp_dh()/SSL_set_tmp_dh(). Most of them use SSL_CTX_set_tmp_dh_callback()/SSL_set_tmp_dh_callback() without setting the key. This has the same effect as setting SSL_OP_SINGLE_DH_USE.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v2 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 5.8 | 2.6 | N/A |
| Attack Vector | Network | Network | N/A |
| Access Complexity | Medium | High | N/A |
| Authentication | None | None | N/A |
| Confidentiality Impact | Partial | Partial | N/A |
| Integrity Impact | Partial | None | N/A |
| Availability Impact | None | None | N/A |
Vector
Red Hat: AV:N/AC:M/Au:N/C:P/I:P/A:N
NVD: AV:N/AC:H/Au:N/C:P/I:N/A:N
Acknowledgements
Red Hat would like to thank OpenSSL project for reporting this issue. Upstream acknowledges Antonio Sanso as the original reporter.
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